The two parcels of seabed India put up for auction on 1 October 2026 contain rock that grew at a rate of a few millimetres per million years.
That is not a misprint. Polymetallic nodules and crusts accumulate metal from seawater so slowly that a nodule the size of a potato may have taken ten million years to form. Which produces an awkward fact about seabed mining that no amount of policy enthusiasm dissolves: these deposits are, on any human timescale, non-renewable in the strictest possible sense. What is removed will not re-form.
Shri Keshav Chandra, Secretary, Ministry of Mines, virtually launched the auction of two offshore mineral blocks in the Andaman Sea for the grant of a Composite Licence, alongside Shri Kadam Sandeep Vasant, Joint Secretary and Administering Authority.
The blocks
| Block | Location | Minerals |
|---|---|---|
| Sewell Rise-01 | Southern part of Sewell Rise, Andaman Sea | Polymetallic nodules and crusts |
| West Sewell Ridge-01 | Off Great Nicobar Island, Andaman Sea | Polymetallic nodules and crusts |
Together they cover over 1,632 square kilometres. The minerals hosted include cobalt, nickel, manganese, copper and rare earth elements — a list that reads as an inventory of what battery manufacture, electronics and clean-energy technology require.
How this rock forms
Two deposit types are named, and they are not the same thing.
Polymetallic nodules sit on the abyssal plain — the deep, flat, sediment-covered floor of the ocean. They are roughly potato-shaped concretions that grow by hydrogenetic precipitation: metals dissolved in seawater, present in vanishingly small concentrations, precipitate onto a nucleus — a shark's tooth, a shell fragment, a piece of older nodule — in concentric layers of manganese and iron oxides, carrying cobalt, nickel, copper and rare earths with them. They lie on the sediment rather than buried in it, which is why they can in principle be collected rather than excavated.
Cobalt-rich crusts form differently. They precipitate from seawater onto exposed hard rock — the flanks and summits of seamounts and ridges swept clear of sediment by currents. A crust is a pavement, millimetres to centimetres thick, plated onto the rock beneath. Crusts are typically richer in cobalt than nodules and poorer in nickel and copper, and they are harder to recover precisely because they are attached to bedrock rather than lying loose.
That a single block contains both tells you something about its topography: Sewell Rise and West Sewell Ridge are elevated features, which is where crusts grow, with sediment-floored areas adjacent, which is where nodules grow.
The Andaman Sea itself is a geologically active back-arc basin behind the Sunda subduction zone, where the Indian Plate descends beneath the Burma and Sunda plates. That setting produces the volcanic seamounts, spreading centres and hydrothermal activity which make the region prospective — and which also make it seismically lively. India's only active volcano, Barren Island, sits in this sea.
The law
The auction is conducted under the Offshore Areas Mineral (Development and Regulation) Act, 2002 and the Offshore Areas Mineral (Auction) Rules, 2024.
The distinction from onshore mining is jurisdictional and worth getting right. Minerals on land are a State subject in important respects, with state governments granting leases. Offshore areas are not within any state's territory: they are the territorial waters, continental shelf and exclusive economic zone, which are Union territory under the Constitution. Offshore minerals are therefore regulated entirely by the Centre, and the Ministry of Mines grants the licences directly.
The Composite Licence being auctioned combines exploration and production rights in a single instrument — the holder may explore and, on establishing a resource, proceed to production without a separate application. For a frontier area where nobody yet knows what is economically recoverable, that matters: a company will not spend on exploration if a competitor can bid for the production rights to whatever it finds.
Note also what this is not. These blocks lie within India's own offshore jurisdiction. They are legally distinct from the deep seabed beyond national jurisdiction — "the Area" — which is administered by the International Seabed Authority, and where India holds exploration rights for polymetallic nodules in the Central Indian Ocean Basin. Two different legal regimes, two different sets of obligations, and papers test the difference.
The auction timeline: tender documents on sale from 1 October 2026; pre-bid conference 4 November 2026; last date for queries 13 November 2026; last date to purchase tender documents 21 December 2026; bid submission by 28 December 2026. The process runs as a transparent electronic auction on the MSTC platform.
Three things worth being sober about
The Secretary's own framing stressed "scientific, technological and environmentally responsible development", and each of those words covers a real difficulty.
Technology. Nobody has yet conducted commercial-scale seabed mining anywhere. Collecting nodules from several thousand metres of water, raising them to the surface, and doing so economically remains unproven at scale. India's own deep-ocean capability is being built through the Deep Ocean Mission and the Matsya submersible and through purpose-built vessels like the ocean research ship Sagar Manthan, but capability for exploration is not the same as capability for extraction.
Ecology. The deep seabed is not empty. Nodule fields host specialised fauna, much of it undescribed, and a nodule is itself a hard substrate on which organisms live in an environment otherwise composed of soft sediment. Removing the nodules removes the habitat, and sediment plumes raised by collection can travel. Because the deposits regenerate at millimetres per million years, recovery of a mined area is not a question of decades. A number of states have called for moratoriums on seabed mining in international waters on exactly this reasoning.
Economics. Metal prices determine whether any of this is viable, and cobalt and nickel prices have been volatile. A deposit that is economic at one price is a stranded asset at another.
None of which argues against exploring. India imports most of the critical minerals it needs, and the strategic case for knowing what lies within its own jurisdiction — set out in the context of India's critical mineral auctions — is strong on its own terms. Exploration establishes what is there; it does not commit anyone to extracting it. The distinction between a Composite Licence granted and a mine opened is years of work and several unsolved problems wide, and that is the honest way to read this auction.
🔑 Revision block
- 1 October 2026: Ministry of Mines launched the auction of two offshore mineral blocks in the Andaman Sea for a Composite Licence. Secretary Shri Keshav Chandra; JS and Administering Authority Shri Kadam Sandeep Vasant.
- Blocks: Sewell Rise-01 (southern part of Sewell Rise) and West Sewell Ridge-01 (off Great Nicobar Island). Combined area over 1,632 sq km.
- Minerals: polymetallic nodules and crusts, hosting cobalt, nickel, manganese, copper and rare earth elements.
- Polymetallic nodules: potato-shaped concretions on the abyssal plain, formed by hydrogenetic precipitation of manganese and iron oxides in concentric layers around a nucleus; lie on the sediment.
- Cobalt-rich crusts: pavements precipitated onto exposed hard rock of seamounts and ridges; typically richer in cobalt, poorer in nickel and copper; harder to recover because attached to bedrock.
- Both grow at a few millimetres per million years.
- Andaman Sea is a back-arc basin behind the Sunda subduction zone; Barren Island, India's only active volcano, lies in this sea.
- Law: Offshore Areas Mineral (Development and Regulation) Act, 2002 and Offshore Areas Mineral (Auction) Rules, 2024.
- Jurisdiction: offshore areas — territorial waters, continental shelf and EEZ — are Union territory, so offshore minerals are regulated entirely by the Centre, unlike onshore minerals where States grant leases.
- Composite Licence combines exploration and production rights in one instrument — essential in a frontier area, so that an explorer is not outbid for what it discovers.
- Distinguish: these blocks are within India's own jurisdiction. The deep seabed beyond national jurisdiction ("the Area") is administered by the International Seabed Authority, where India holds nodule exploration rights in the Central Indian Ocean Basin.
- Timeline: tender documents from 1 October 2026; pre-bid conference 4 November 2026; queries by 13 November; tender purchase by 21 December; bids by 28 December 2026. Conducted on the MSTC platform.
🎯 Practice MCQs
Q1. The two offshore mineral blocks put up for auction are located in the: (a) Gulf of Mannar (b) Arabian Sea off Kerala (c) Andaman Sea (d) Gulf of Kutch
→ (c) Sewell Rise-01 and West Sewell Ridge-01 are both in the Andaman Sea, the latter off Great Nicobar Island, covering over 1,632 sq km between them.
Q2. Polymetallic nodules are characteristically found: (a) Lying on the sediment of deep abyssal plains (b) Embedded within continental shelf sandstones (c) In hydrothermal vent chimneys (d) Plated onto the exposed rock of seamount summits
→ (a) Nodules lie on the sediment of the abyssal plain, which is why they can in principle be collected rather than excavated. Option (d) describes cobalt-rich crusts, the other deposit type named in the auction.
Q3. Cobalt-rich crusts differ from polymetallic nodules principally in that crusts: (a) Contain no manganese (b) Form on exposed hard rock of seamounts and ridges rather than on sediment (c) Are found only in fresh water (d) Form through volcanic eruption rather than precipitation
→ (b) Crusts precipitate onto exposed hard rock swept clear of sediment by currents, forming a pavement attached to bedrock. Both deposit types form by precipitation from seawater and both contain manganese.
Q4. The rate at which polymetallic nodules and crusts accumulate is of the order of: (a) A few millimetres per million years (b) A few centimetres per century (c) Several centimetres per year (d) A metre per millennium
→ (a) A few millimetres per million years — among the slowest geological processes known, and the reason a mined nodule field cannot recover on any human timescale.
Q5. Offshore mineral resources in India are regulated entirely by the Union Government because: (a) Minerals are a subject in the Union List in all cases (b) State governments have surrendered their powers by agreement (c) The Mines and Minerals (Development and Regulation) Act does not apply to minerals (d) Territorial waters, the continental shelf and the EEZ are not within the territory of any State
→ (d) Offshore areas lie outside any State's territory and are Union territory, so the Centre grants licences directly. Onshore, by contrast, State governments grant mineral leases.
Q6. The auction is being conducted under which legislation? (a) The Mines and Minerals (Development and Regulation) Act, 1957 (b) The Offshore Areas Mineral (Development and Regulation) Act, 2002 (c) The Territorial Waters and Maritime Zones Act, 1976 (d) The Coastal Regulation Zone Notification, 2019
→ (b) The Offshore Areas Mineral (Development and Regulation) Act, 2002, with the Offshore Areas Mineral (Auction) Rules, 2024. The MMDR Act 1957 governs onshore minerals.
Q7. A 'Composite Licence' in this context is significant because it: (a) Permits mining of more than one mineral from the same block (b) Allows a foreign company to bid without an Indian partner (c) Combines exploration and production rights in a single instrument (d) Exempts the holder from environmental clearance
→ (c) It combines exploration and production rights, so an explorer who establishes a resource may proceed to production without a fresh competitive process. In a frontier area that assurance is what makes exploration spending rational.
Q8. The deep seabed beyond the limits of national jurisdiction is administered by the: (a) International Maritime Organization (b) Food and Agriculture Organization (c) United Nations Environment Programme (d) International Seabed Authority
→ (d) The International Seabed Authority administers "the Area" beyond national jurisdiction, where India holds exploration rights for polymetallic nodules in the Central Indian Ocean Basin. The blocks now auctioned lie within India's own jurisdiction — a different legal regime.
Q9. The Andaman Sea's prospectivity for seabed minerals is linked to its setting as a: (a) Passive continental margin (b) Back-arc basin behind the Sunda subduction zone (c) Mid-ocean ridge spreading at a fast rate (d) Closed evaporite basin
→ (b) It is a back-arc basin behind the Sunda subduction zone, a setting that produces volcanic seamounts, spreading centres and hydrothermal activity. Barren Island, India's only active volcano, lies in this sea.
Q10. The principal ecological concern specific to nodule collection is that: (a) Nodules are themselves a hard substrate habitat in an otherwise soft-sediment environment (b) Collection raises the temperature of the deep ocean (c) Nodules release methane when disturbed (d) Nodule fields are the principal breeding grounds of commercial fish stocks
→ (a) In a seafloor otherwise made of soft sediment, each nodule is a hard surface on which specialised organisms live. Removing the nodules removes the habitat, and because they regenerate at millimetres per million years, the loss is effectively permanent.
📋 How this gets asked (PYQ pattern)
Earth science and ocean resources appear steadily in the NDA paper, and this story touches the three most examined areas.
The first is seafloor features and where things form: continental shelf, slope, rise, abyssal plain, mid-ocean ridge, trench, seamount, guyot. Nodules on abyssal plains, crusts on seamounts, massive sulphides at hydrothermal vents. Match the deposit to the feature and a whole family of questions becomes answerable.
The second is maritime zones, which is pure definition and pure marks. Baseline, territorial waters to 12 nautical miles, contiguous zone to 24, exclusive economic zone to 200, continental shelf, and the Area beyond. Each confers different rights, and the auction-versus-ISA distinction in this story rests entirely on that ladder.
The third is critical minerals, now a standing theme. Cobalt, nickel, lithium, manganese, copper and the rare earth elements — what they are used for, where India sources them, and which institutions handle them. Note that "rare earth elements" are not actually rare in crustal abundance; they are difficult and polluting to separate, which is the real constraint and a favourite question.
A fourth pattern is plate tectonics applied to a named place. The Andaman Sea as a back-arc basin, Barren Island as India's only active volcano, the Sunda subduction zone, and the 2004 tsunami's origin on the same plate boundary. Questions often give the place and ask for the tectonic setting, or the reverse.
Preparing for NDA? For ocean resources, build one diagram in your head — the seafloor profile from coast to abyss — and place every feature, maritime zone and deposit type on it. Most questions in this area are a request to read that diagram. Build the base with our NDA general ability notes, follow the daily NDA current affairs, and prepare with our faculty in the upcoming Cavalier courses in Delhi.
✍️ Written by Col Vijyanat Thakur — Defence studies faculty at The Cavalier. Reviewed by the Cavalier Faculty Desk.